Piston



P 1953 J. c. APPLETON 2,653,065

PISTON .Filed Aug. 22. 1949 Aiiwmegs Patented Sept. 22, 1953 UNITEDSTATES PATENT OFFICE 3 Claims.

This invention relates to pistons for four cycle internal combustionengines.

It is one of the objects of the invention to provide a novel andimproved piston so constructed as to permit of proper lubrication of thecylinder wall and which at the same time will not permit pumping of oilpast the uppermost ring or the piston during the intake stroke ofthepiston.

With the ordinary piston used in a four cycle internal combustionengine, if during the intake stroke the throttle after being pushed waydown is suddenly released so as to out oii a supply of fuel to thecylinder before the intake stroke has proceeded very far, the vacuumpressure in the head of the cylinder will be very high and underordinary circumstances this vacuum pressure may be high enough to causeoil to be drawn up above the head of the piston around the upper ringresulting in what is commonly referred to as oil pumping and the burningof oil and exeessive formation of carbon during the explosion stroke.

It is a more specific object of the invention to provide a pistonconstruction so made as to partially relieve excessive vacuum pressuresin the cylinder head during the intake stroke to prevent oil pumping bypermitting the travel of gases from the interior of the piston aroundthe uppermost ring carried by the piston to the head of the piston.

For some time automotive engineers have been attempting to very greatlyincrease the explosive forces in th cylinder of an internal combustionengine during the power stroke without at the same time increasing thevacuum pressure in the head of the cylinder during the intake strokewhich would tend to cause oil pumping.

It is another object of the invention to provide a piston so constructedthat th maximum vacuum pressure in the head of the cylinder during the,intake stroke can be regulated, thereby pernitting the powerof theexplosion stroke to be greatly increased without prcducingoil propping.

The objects and advantages of the invention will more fully appear fromthe following descrip tion made in connection with the accompanyingdrawing wherein like reference characters refer to the same or similarparts throughout the different views, and in which:

Fig. l is a view in vertical section showing a portion of a four cycleinternal combustion engine provided with a piston embodyin the presentinvention, the piston being shown in side elevation;

Fig. 2 is a vertical section in enlarged scale through the piston andportions oi the cylinder ignated by the numeral 26. 55

walls showing the parts of the piston as they will appear during thepower portion of the explosion stroke of the engine;

Fig. 3 is a generally similar View showing the parts as they will appearduring the intake stroke and the explosion stroke after the power of theexplosion stroke has been spent;

Fig. 4 is a generally similar view showing the parts as they will appearduring th compression and exhaust strokes;

In Figs. 1, 2, and 3 the clearance for up and down movement of the ringsin the Various. ring grooves of the piston is greatly exaggerated forthe purpose of illustrating the relative positioning of the differentrings in the grooves during the difierent strokes or portions thereof ofthe piston; and

Fig. 5 is a perspective view illustrating the upper piston ring as shownin the other views of the drawing.

Referring to'the. drawings, there is there shown portions of a fourcycle internal combustion engine including the engine block 6 having acylinder l formed therein, the block being closed at its top by theusual cylinder head 13 and this head having a passage 9 running from thefuel intake passage Iii controlled by the intake valve H to the head ofthe cylinder 1. One of the spark plugs i2 is also shown, as is one ofthe connecting rods l3 of the engine and one of the pins i l forattachment of the connecting rod to a piston.

In accordance with, the present invention, there is provided a piston ofspecial construction, this piston being designated generally by theletter A. The said piston, as is usual, includes a head it and a hollowcylindrical wall it terminating in a skirt ll. 'Ih piston, accordingly,forms in the usual manner an internal chamber 3i which is open at thebottom of the piston. In the peripheral surface of the Wall of thepiston there is out an upper ring groove 58, an intermediate ring grooveis and a lower ring groove 2t, and the exterior portions of the wall ofthe piston between the several grooves and between the upper groove andthetop of the piston form an upper land 2!,

an intermediate land 22, and a lower land 23. For ready reference thelower surface of the upper land 2i and, accordingly, the upper wall ofthe upper ring groove E8 is designated 2Q, while the vertical wallbetween the upper land 2! and the lower land 22 forming the bottom ofthe groove H5 is designated by the numeral 25. The upper wall of theintermediate land 22, i. e., the next-to-the-uppermost'land of thepiston, is des The spacing between thev upper groove 18 and 3 theintermediate groove 19 is slightly greater than is found in mostpistons, and this is for the special purpose of the boring of a numberof diagonal passages 21 through the wall of the piston and for theinsertion through the uppermost groove 25 of bits for this purpose inline with the passages to be formed. These passages 23 extend throughfrom the surface 26 to the chamber I8, the upper ends of the passagesbeing located intermediate the inner and outer portions of the surface26. The wall of the piston A is stepped at 28 and again at 29 so thatthe wall is considerably thicker above the skirt l'i face, and thepurpose of making the said surface 2+ substantially normal to thepassages 21 is to prevent the breakage of drills during the formation ofthe passages 21 while preserving the accuracy of the bore. The pistonpin 14 which carries the connecting rod I3 is connected to the skirt llof the piston in the usual manner.

Fitted within the two lower grooves l9 and 2%) of the piston in theusual manner are ordinary piston rings 3! and 32 of any standardconstruction, these rings having the usual very slight clearances withinthe grooves l9 and for very limited up and down movement in thesegrooves.

Fitted within the uppermost ring groove [8 is a split piston ring 33 ofspecial construction.

This ring 33 as is best illustrated in Fig. 5 has a i top surface 33aequipped with a plurality of shallow radially extending channels 331)out therein. The ring itself is fitted into the upper groove [8 so as tohave a clearance for up and down movement in this groove which isbetween .0015 and .003 inch. Such clearance is quite essential to thepresent construction in order to permit the lower surface of the upperring 33 to have a cooperative valve action with the upper openings inthe passages 21 at the point where these openings are formed in thesurface 26. Of course, the ring 33 is a compression ring and there isthus always formed between the inner surface of this ring and thesurface of the piston a short vertical passage.

Considering first the intake stroke of the piston A in the cylinder, asthe piston moves downwardly in the cylinder in the direction of thearrow shown in Fig. 3, the three rings 33, 3!, and i2 tend to dragrelative to the piston A, and, hence, the upper surfaces of the threerings will ride against the under surfaces of the three lands 2 I, 22,and 23 as illustrated in Fig. 3.

A very important function is accomplished by the present piston duringthe intake stroke. As high vacuum is created in the head of the cylinderabove the upper ring 33, excessive vacuum may be relieved by the passageof gases from the chamber !8 of the piston upwardly through the passages21, which are now uncovered, around between the inner side of the upperring 33 and the surface 25 of the piston and through the channels 33bformed at the top of the upper ring 33. These gases will carry with themoil vapor from the crank case to. lubricate the top The upper step 29 ismade to give surface 33a of the top ring 33 and the under surface 24 oftop land 2|. By accurately gauging the depth to which the channels 33?)are out and providing the requisite number of these channels andproviding passages 2'! of the proper number and size, it is possible toregulate the maximum negative pressure to which the head of the cylinderis subjected during the intake stroke before this pressure is relievedby the passages described from the chamber of the piston to the head ofthe cylinder. This permits exceedingly high explosive pressures to bedeveloped in the cylinder during the explosion stroke and yet preventsexcessive vacuum during the suction stroke and, of course, eliminateswhat is commonly known as oil pumping. In other words, the presentconstruction is adapted for use in very high compression motors withoutproducing oil pumping.

During the compression stroke of the piston the parts will appear asshown in Fig. 4, the piston moving in the direction indicated by thearrow on that view. As the piston moves upwardly to compress the gasesin the cylinder all three rings, 33, 31 and 32 will bear against thelower surfaces of the grooves l8, I9 and 28, respectively, and,accordingly, the under surface of the upper ring 33 will seal againstthe surface 23, thereby closing the upper ends of the passages 25 toprevent the gases being compressed to run through the passages 21 intothe chamber 34 of the piston.

During the power portion of the explosion stroke of the piston the partswill appear as shown in Fig. 2, the piston, of course, moving in adownward direction as indicated by the arrow on that view. The pressuredeveloped during the power portion of the explosion stroke in the headof the cylinder is sufficient to force the upper ring 33 into contactwith the surface 26 of the piston, thereby sealing the passages 21 andpreventing blowing of the compressed explosive gases through thepassages 2? into the chamber 34 of the piston and thence into the crankcase. The two lower rings 31 and 32 dragging relative to the piston Ahave their upper surfaces in contact with the lower surfaces of therespective lands 22 and 23 as indicated in Fig. 2 during the powerportion of the explosive stroke and during the entire stroke, for thatmatter. During the latter portion of the explosion stroke after theexplosive forces have been largely spent relatively light pressure isapplied against the upper surface of the upper ring 33 and the uppersurface of the upper ring will move into contact with the surface 2 10fthe piston as is shown in Fig. 3.

During the exhaust stroke of the piston the parts will again assume theposition as shown in Fig. 4. At this time the upper ring 33 will sealthe passages as so as to prevent exhaust gases from escaping into thechamber 34 of the piston and thence into the crank case.

The peculiar action to prevent oil pumping of the engine is accomplishedonly when the passages 21 run from the upper ring groove i8 and when theupper ring provided has the limited clearance for slight up and downmovement in the upper ring groove. The relief of suction pressure in thehead of the cylinder is accomplished only when the upper ring isprovided with the channels 33b or equivalent means.

It will be seen that a highly effective piston has been provided for usein four cycle internal combustion engines.

It will, of course, be understood that various changes may be made inthe form, details, arrangement, and. proportions of the various partswithout departure from the scope of the present invention, which,generally stated, consists in the matter shown, and described, and setforth in the appended claims.

What I claim is:

1. A piston for four cycle internal combustion engines, said pistonhaving an internal bottom opening chamber, a plurality of spaced ringgrooves cut in the peripheral wall thereof and lands formed between saidring grooves and above the uppermost ring groove, said piston having aplurality of passages running only from the top surface of thenext-to-the-uppermost land intermediate the periphery of said land andthe bottom of the uppermost groove into the chamber of the piston, ringsfitting within said .ring grooves, the uppermost ring having a limitedvertical play within the uppermost groove and the lower surface of theuppermost ring co- Operating as a valve with the upper ends of saidpassages at the top surface of the next-to-theuppermost land to sealsaid passages during the power portion of the explosion stroke of theengine and during the compression and exhaust strokes, the saiduppermost ring during the intake stroke and the spent portion of theexplosion stroke moving away from the top surface of the .next to theuppermost land, and means cooperatively associated with the uppermostring and the uppermost land to afford communication between the cylinderabove the piston and the upper ends of said passages when said uppermost.ring is shifted into extreme upper position within its groove therebypreventing the pumping of aoil into the head of the cylinder above thepiston.

2. The structure defined in claim 1, said passages being inclined andforming straight passages through said uppermost groove to the internalside of said piston.

3. A piston for four cycle internal combustion engines, said pistonhaving an internal bottom opening chamber, a plurality of spaced ringgrooves out in the peripheral wall thereof and lands formed between saidring grooves and above the uppermost ring groove, said piston having aplurality of passages running only from the top surface of thenext-to-the-uppermost land intermediate the periphery of said land andbottom of the uppermost groove into the chamber of the piston, ringsfitting Within said ring grooves, the uppermost ring having a limitedvertical play within the uppermost groove and the upper surface of theuppermost ring having a plurality of shallow cross channels therein, thelower surface of the uppermost ring cooperating as a valve with the endsof said passages at the top surface of said next-to-the-uppermost landto seal said passages during the power portion of the explosion strokeof the engine and during the compression and exhaust strokes, saiduppermost ring during the intake stroke and the spent portion of theexplosion stroke moving away from the top surface of thenext-to-theuppermost land, said cross channels cooperating with thebottom portion of the uppermost groove and said passages to formcontinuous passages around the uppermost ring into the chamber in saidpiston to relieve high suction pressure at the head of the cylinderduring the intake stroke. JAY CLYDE APPLETON.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,365,348 Shetler Jan. 11, 1921 2,054,863 Oliver Sept. 22,1936 2,176,231 Swortwood et al. Oct. 17, 1939 2,396,155 Christensen Jan.30, 1943 2,366,080 Wingate Dec. 26, 1944 2,396,018 Mis Mar. 5, 19462,404,547 Strid July 23, 1946 2,477,760 Mennie Aug. 2, 1949

